1. Field of the Invention
The present invention relates to an inexpensive zoom lens system which can be advantageously used in a compact camera where restrictions on the back focal distance are less restrictive than in a single lens reflex camera.
2. Description of Related Art
A known compact camera having a zoom lens consisting of two lens groups and having a zoom ratio approximately equal to 2, is comprised of either a relatively large number of lenses (6 to 9 lenses) or a relatively small number of aspherical lenses (4 lenses at the most). In the former type, where a large number of lenses are used, it is difficult to reduce the production cost. While in the latter type where a relatively small number of lenses are used, the relationship between the number, and the arrangement of aspherical lenses which are used is still uncertain and in the process of being improved. The applicability of plastic lenses used in conjunction with the aspherical lenses has also been studied. In addition, the production cost of the latter type of zoom lens is not satisfactory. A two-lens group type of zoom lens is also known. This lens group is made of two or three lenses, however the F-number thereof at the telephoto extremity exceeds 10.